Receptacle for electrical connector



Aug. 2, 1960 w. R. FRANCIS ETAL RECEPTACLE FOR ELECTRICAL CONNECTOR Filed Sept. 3, 1957 fi'a. 4. a/z/ 5 all 1 m r a fine/Mars Waflac'e A. Hana/5, Geogfe 6. Me ba/$0 617,

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United States Patent RECEPTACLE FOR ELECTRICAL CONNECTOR Wallace R. Francis, Milford, George C. Mapelsden, Easton, and Cecil W. Feher, Shelton, Comm, assignors to General Electric Company, a corporation of New York Filed Sept. 3, 1957, Ser. No. 681,551

6 Claims. (Cl. 339-'-188) The present invention relates to a receptacle that is to be joined with an electrical connector fastened on an end of an electric cord. Such a receptacle is particularly useful when mounted in a portable electric tool such as a drill, saw, sander, or lawn trimmer.

Up until this time almost all portable electric tools have been provided with a power cord as a permanent part; of the tool. Many such power cords, especially those fer the larger tools, are of heavy cross-section and are diflicult; to foldinto a tool box with the tool. Also, as the average home owner accumulates more electric tools, he hasa sizeable investment in electric cords. Now the portable tool industry is interested in removable cordsets of standard design which may be interchanged with the different tools. A removable cordset must be capable of making a good electrical connection and also be easily removable, but not liable to be removed accidentally.

The principal object of this invention is to provide a receptacle adapted for mating engagement, with an electrical" connector with a positive locking arrangement between the parts.

A further object of this invention is to provide a receptacle of the class described wherein a twisting action is necessary to effect the locking of the parts, there being special provision made to insure that the receptacle will be in a position to receive the connector after the connector is removed.

A further object of this invention is to provide a receptacle of the class described with a novel cylindrical shell that will permit the parts of the receptacle to be assembled through the base of the shell.

A still further object of this invention is to provide a receptacle of the class described with automatic means for turning the connector into a locking position as the connector is forced into the receptacle.

The present invention relates to a receptacle that is particularly adapted to be mounted within the handle or housing of a portable electric tool so that a connector of a power cord may be fitted in the receptacle. The mechanical connection between the connector and the receptacle of the tool must be both substantial and reliable because it should withstand a 35 pound pull test exerted on the cord. Accordingly, a positive locking arrangement is preferable to a straight spring lock. A common type of mechanical lock is a bayonet pin and slot con nection which has been adopted for this invention. The receptacle is provided with a cylindrical metal shell havinga spring base at one end while the opposite end is left open. to receive a cord connector. A bayonet slot is formed inthe wall of the shell and it extends to the edge of the open end of the shell. A connector that is adapted to fit within the shell of the receptacle has a transverse bayonet pin mounted in its side to cooperate with the bayonet slot of the receptacle.

The connector includes two or more female contacts molded therein. The mating pin contacts of the receptacle are mounted on a plunger of insulating material that is confined within the shell of the receptacle. Since ice;

the connector must be twisted in the receptacle to lock the bayonet pin in the slot, the plunger must also be capable of turning. Thus, a pair of cars extend from the opposite sides of the plunger and are confined in inclined slots formed inthe walls of the shell. A coiled spring is seated in the base of the shell to bear against the plunger and normally hold the plunger with its ears positioned in the far ends of the slots. In this position, the pin contacts of the plunger will be properly oriented with relation to the female contacts of the connector as the bayonet pin is being inserted into the bayonet slot of the receptacle. Also, when the connector is being shoved into the receptacle, the plunger will be slightly depressed against the spring until its ears engage the lower edges of the inclined slots. Then the plunger will begin to turn in the shell. Finally, when the pushing force is removed from the connector, the spring in the receptacle will expand in an attempt to return the plunger to its original position. However, instead the bayonet pin of the connector will become entrapped in the bayonet slot, which is the final locking position between the connector and receptacle.

Another important feature of this invention is in the method of assembling the several parts of the receptacle. The base end of the shell is first left open with a series of bendable tabs extending downwardly from the bottom edge of the shell. The inclined slots for guiding the movement'of the plunger have lower extensions that open in the edge of the base of the shell to enable the plunger to be brought: in through the base until the ears are confined within the inclined slots. Then, the coiled spring is inserted into the shell. and against the plunger, and lastly: the tabs are bent inwardly to form a seat for the spring. Our invention will be better understood from the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

Figure l is an isometric view of a small portable electric drill with a receptacle according to this invention mounted in the handle and in mating engagement with the connector of a power cord.

Figure 2 is an exploded view of the receptacle of this invention and a typical grounding connector that is adapted to be inserted in the receptacle.

Figure 3 is a side view of a completely assembled receptacle embodying this invention.

Figure 4 is a showing of the blank of sheet steel from which the cylindrical shell of the receptacle is formed.

Figure 5 is a cross-sectional view taken through the center of the grounding connector of Figure 2 showing the manner of anchoring a bayonet pin in the side of the connector.

Figure 6 is a right end view of the grounding connector of Figure 5.

Referring in detail to the drawing, and in particular to Figure 2, there is shown a cylindrical metal shell 10, a disc-shaped plunger 11 of insulating material and a coiled spring 12. These three elements 10, 11 and 12, comprise the principal elements of the receptacle of the present invention which is shown fully assembled in Figure 3. The function of the receptacle is to make both a mechanical and an electrical connection with a connector 13 thatis formed on one end of a power cord or cordset 14. The mechanical coupling or locking arrangement is performed by the cooperation of a bayonet slot 15 in the wall of the shell 10 and a bayonet pin lfi that extends from one side of the connector 13 near the free end thereof.

As seen in Figures 5 and 6, the connector 13 is1:a grounding connector having three conductors, onejof which is a ground wire. The connector includes three D-sha-ped female contacts or sleeves 18 which are crimped at their terminal ends 19 to the conductors of the cord 14. A fiber insulating sleeve is slipped over each contact 18 to reinforce the contacts because they are rolled into shape from fiat stock and might otherwise become enlarged by the 'pin contacts of the receptacle. The bayonet pin 16 has an inner end that extends between two of the adjacent contacts 18 as best seen in Figure '6. The fiber sleeves 20, however, will insulate the pin 16 from the contacts so as not to short-circuit the cord. The center portion of the pin 16 has a shoulder 17 which anchors the pin in the connector body.

The receptacle has three pin contacts 22 mounted on the plunger 11 for mating engagement with the female contacts 18 of the connector. It should be remembered that in order to lock the bayonet pin 16 of the connector in the bayonet slot 15 of the receptacle it is necessary to twist the connector until the bayonet pin 16 is lodged in the concave seat identified as 21. Accordingly, it is not feasible to fix the plunger 11 in the shell 10 because the plunger must be capable of turning with the connector. A pair of ears 23 extend from opposite sides of the plunger 11 and are confined Within inclined slots 24 in the walls of the metal shell 10. The inclined edges of each slot 24 are parallel to each other and arranged at an angle of approximately 60 to the longitudinal axis of the shell 10 as seen in Figure 4. The ears 23 of the plunger also have inclined top and bottom sides which correspond with the inclined edges of the slots 24. The lower ends of the inclined slots 24 extend downwardly toward the base end of the shell. The plunger 11 is assembled in the shell 10 by inserting the ears 23 of the plunger through the base of the shell and'into the slots 24. As seen in Figure 2, lead wires 26 are attached in the plunger 11 to the pin contacts 22 and extend downwardly therefrom. The plunger 11 is held in position by means of the coiled spring 12 that is likewise inserted through the base 25 of the shell. The lower edge of'the shell 10 at the base end 25 is provided with a series of bendable tabs 27 which are turned inwardly after the spring 12 is assembled to serve as a seat for the spring. The lead wires 26 are brought out through the center of the spring and between the tabs 27.

Turning now to a consideration of Figures'2 and 3 for an understanding of the movement of the plunger 11, the several motions of the parts during the insertion of the connector 13 into the shell of the receptacle Will be discussed.

First, the bayonet pin 16 of the connector is aligned with the open end of the bayonet slot 15 of the shell 10. The connector is then pushed intothe shell and the female contacts 18 will drop over the pin contacts 22 and the plunger 11 will be forced inwardly of the shell against the action of the coiled spring 12. As seen in Figure 3 the parallel inclined edges of the slots 24 are further apart than the depth of the ears 23. Hence, as the plunger 11 moves back into the shell 10, the ears 23 will strike against the lower inclined edges and tend to slide on that lower surface. In so doing, the plunger 11 will turn in the shell until the bayonet pin 16 strikes the side of the bayonet slot. At this point the connector should be released so the spring 12 will force the plunger 11 upward and the bayonet pin 16 will become latched in the seat 21. Touncouple the connector 13, it is again forced inwardly of the shell 10 until the bayonet pin-is driven out of the seat 21 and'a reverse twist is given to the connector so that the bayonet pin 16 will slide out through the slot 15. As the connector 13 is being disengaged from the shell 10, the ears 23 of the plunger 11 are in the position shown in Figure 3. The upward force of the spring 12 'on the plunger 11 and the upwardinclination of the upper edges of the slots 24 cooperate to turn the plunger until the ears 23 are in the far ends of the slots 24. i i

' The shell of the receptacle of this invention has a pair of lanced tabs struck from opposite sides of the shell 2,947,966 p a a g 4 near the open end thereof. Each tab has a small opening 31 for receiving a fastening screw (not shown) that will attach the receptacle in place. The tabs are formed outwardly to lie within a common horizontal plane but it should be understood that this mounting means forms no part of the present invention.

Having described above our invention of a novel receptacle for an electric cord connector, it should be realized by those skilled in this art that this design is both simple and easy to manufacture as well as being reliable in operation. While the lower edges of the inclined slots 24 have been described as the elements which force the connector to turn in the shell, another modification would be to'have the bayonet pin 16 strike the inclined bottom edge of the bayonet slot 15. In this case the opposite cars 23 of the plunger would not engage the lower edges of the slots 24 at all. Also, if a person were careful it would be possible to insert the connector into the shell and lock the connector in place without this automatic turning feature.

The upper edges of the inclined slots 24 are of primary importance because they serve to position the ears 23 of the plunger at the far end of the slots due to the action of the spring 12. This spring is relatively stiff so that it is practically impossible to insert a finger or a tool into the shell and rotate the plunger where it might be caught in an intermediate position which would not accept the bayonet pin and female contacts of the con nector 13.

Modifications of this invention will occur to those skilled in this art and it is to be understood, therefore, that this invention is not limited to the particular embondiments disclosed and that it is intended by the ap-' pended claims to cover all modifications which are withiri the true spirit and scope of this invention. 7

What we claim as new and desire to secure by Letters Patent of the United States is:

1. An electrical receptacle comprising a cylindrical shell having at least one bayonet slot that is open at one end of the shell, a plunger of insulating material positioned in the shell, a pair of ears extending from the sides of the plunger, and a pair of inclined slots formed on diametrically opposite sides of the shell for receiving the said ears of the plunger, spring means seated in the other end of the shell and bearing against the plunger to urge the ears to the far ends of the slots due to the inclination of the slots, and electrical contacts mounted in the plunger and arranged for mating engagement with contacts of an electrical connector to physically couple said plunger to said connector for simultaneous rotation, said bayonet slot serving as means for cooperation of said connector with said receptacle, at least one of said bayonet and inclined slots being arranged to turn saidplunger and said connector toward a locked position upon movement of said connector and plunger after the initial engagement thereof. V

2. An electrical receptacle as recited in claim 1 in combination with an electrical connector that has a bayonet pin for locking engagement in the said bayonet slot, a downwardly sloping surface at the bottom of the bayonet slot so that when the connector is thrust into the receptacle, the pin will engage the said sloping surface and be forced to slide down such surface thereby automatically turning the connector toward a locking position. i i

3. An electrical receptacle for a portable tool com prising a cylindrical shell having at least one bayonet slot that is open at one end of the shell for cooperation with a bayonet pin of a connector so that they may be locked together, a plunger of insulating material positioned in the shell beyond the bayonet slot, at least two pin contacts mounted on said plunger and arranged for mating engagement with said connector, a pair of ears formed on the sides of the plunger, and a pair of op;- positely inclined slotsformed on diametrically opposite sides of the shell, the ears of the plunger being confined within the said inclined slots and guided thereby, and spring means seated in the opposite end of the shell to bear against the plunger and urge it to turn until the ears are situated in the far ends of the slots, at least one of said bayonet and inclined slots being arranged to turn said plunger and said connector toward a locked position upon movement of said connector and plunger after the initial engagement thereof.

4. An electrical receptacle as recited in claim 3 with the addition of a male connector for insert-ion within the shell, the connector including at least two female contacts for engagement with the pin contacts of the receptacle, a bayonet pin extending from one side of the connector for cooperation with the bayonet slot of the receptacle, the said spring serving to turn the plunger so that the pin contacts of the receptacle will be in the proper position to receive the female contacts of the connector when the bayonet pin is being inserted in the bayonet slot.

5. An electrical receptacle and connector for a portable tool comprising in combination a cylindrical metal shell for a receptacle, the shell having a base at one end and being open at the other end, a bayonet slot in the shell adjacent the open end, a plunger of insulating material positioned in the shell intermediate the base and open end, a pair of oppositely directed ears on the sides of the plunger, and a pair of inclined slots formed on diametrically opposite sides of the shell for receiving the said ears of the plunger, each ear having inclined surfaces that are parallel to the inclined edges of the mating slot, and spring means seated in the base of the shell and hearing at its opposite end against the plunger to bias the plunger to turn in the shell until the ears are situated in the :far ends of the inclined slots, at least two pin contacts mounted on the plunger on the side adjacent the open end of the shell, and lead wires extending through the base of the shell and through the said spring for termination with the said pin contacts on the plunger, the connector comprising a cylindrical plug of insulating material having at least two female contacts provided therein, and a bayonet pin adjacent the end of the connector containing the contacts, so that when the bayonet pin is aligned in the bayonet slot of the receptacle the connector may be forced into the receptacle thereby bringing the several contacts into engagement and depressing the plunger against the spring so that the ears of the plunger will turn as they slide down the edges of the inclined slots, whereby a locking engagement is effected by the bayonet slot when the connector is released as the spring forces the plunger toward the open end of the shell in an attempt to return the plunger to its original position.

6. An electrical receptacle and connector for a portable tool as recited in claim 5 wherein the said pair of inclined slots each have a slotted portion that extends to the base end of the shell, and a plurality of tabs formed on the base end of the shell so that the ears of the plunger may be inserted into the inclined slots from the base end of the shell, and the spring pressing against the plunger and held in place by the tabs being bent inwardly toward each other.

References Cited in the file of this: patent UNITED STATES PATENTS 1,304,075 Lofgren May 20, 1919 1,678,138 Douglas July 24, 1928 1,803,709 Johnson May 5, 193 1 

